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Our salts for analysis are manufactured under strict production guidelines. Analytical purity and best quality reliably characterize each batch. Salts in p.a. quality made by Carl ROTH meet the high requirements for reproducible results. Most of our salts are additionally specified according to international standards like ACS and ISO.
Definition:p.a.: pro analysi (for analysis)ACS: American Chemical SocietyISO: International Standard Organisation
For pesticide residue analysis in food
Within a few years after its development the QuEChERS method (Quick, Easy, Cheap, Efficient, Rugged, Safe) has gained a leading position for determination of pesticide residues in food samples by GC-MS or LC-MS, allowing rapid and cheap clean-up of strongly matrix-contaminated samples. For optimizing the extraction of pH-dependent compounds, for minimizing decomposition of sensitive substances, and for broadening the matrix spectrum,different modifications of the QuEChERS method have been elaborated.
In addition to the required adsorbent Silica gel 60 diamino a number of individually weighed and premixed buffer and extraction mixtures is offered, specially composed for different sample matrices.
For extraction, the European standard EN 15662 recommends a citrate extraction mix (Mix I), while AOAC standard 2007.1 uses an acetate extraction mix (Mix II). For clean-up, the Diamino phase (PSA) removes, e.g., sugars and organic acids. Magnesium sulfate removes water, C18 ec removes non-polar interferences such as fats and the carbon phase removes pigments, sterols, and non-polar interferences. For selection of the proper clean-up mix see table below.
Adsorbents and what their use
MgSO4 | Removes excess of water |
NaCl | For phase separation |
Silica Gel 60 Diamino (PSA) (Primary Secondary Amine) |
Removes organic and fatty acids, sugars and anthocyanin pigments |
Silica Gel 60 C18 ec (reversed phase modified silica) |
Traps nonpolar compounds, e.g., lipids |
Carbon (GCB) (Activated Charcoal / Graphitized Carbon Black) |
Removes pigments and sterols (please note: planar pesticides are also removed) |
Assay (perchloric acidim) | ≥99,0 % |
pH-value (5 %, water) | 7,5-9,0 |
In H2O insoluble matter | ≤0,003 % |
Chloride (Cl) | ≤0,003 % |
Phosphate (PO4) | ≤0,005 % |
Sulphate (SO4) | ≤0,005 % |
Oxalate (as C2H2O4) | ≤0,01 % |
Ammonium (NH4) | ≤0,001 % |
Arsenic (As) | ≤0,00004 % |
Lead (Pb) | ≤0,0005 % |
Calcium (Ca) | ≤0,005 % |
Iron (Fe) | ≤0,0005 % |
Copper (Cu) | ≤0,0005 % |
Nickel (Ni) | ≤0,0005 % |
Heavy metals (as Pb) | ≤0,0005 % |